The present invention relates to a fastening device for a safety belt used in escaping or mountaineering or for seat belt of a car or the like. The fastening device is fitted with the a safety belt to form a fastening loop. The fastening device can be quickly slid along the fastening loop to adjust the size thereof to suit different body dimensions. The fastening device permits a user to quickly fit the fastening loop onto his/her body and can be quickly shifted to tighten the user's body in an emergency. After being fastened and located, the biting plates of the fastening device bite the belt body to prevent the belt body from loosening so as to ensure safety.
FIGS. 1 and 2 show an escaping suspension pulley 10 installed at the porch of a building. The suspension pulley 10 is hung on a safety hook 20 fixed on the wall. Two straps 11 downwardly extend from the suspension pulley 10. The end of each strap is formed as a fastening loop 12 tied with a substantially B-shaped adjustable fastening buckle 30. FIGS. 3 and 4 show two existing types of the fastening buckles, wherein in FIG. 3, the fastening buckle is plane, while in FIG. 4, the fastening buckle is curved. The fastening buckle 30 can be slid along the strap for adjusting the size of the fastening loop 12 for tightening the waist section of a user as shown in FIG. 1. Accordingly, as shown in FIG. 4, the user is suspended and able to slowly move down from the porch for escaping in an emergency.
The above conventional fastening buckles 30 are freely movably fitted with the strap, while lacking a securing force. Therefore, when the fastening loop 12 tightens the waist section as shown in FIG. 1. the fastening buckle 38 tends to slip away to enlarge the fastening loop 12. At this time, in case the user just raises his/her both hands, the user may come loose from the fastening loop 12 to drop down.